Recently, there are great expectations towards applications of organic EL devices in full-color display devices. As one method for full-color displays using an organic EL device, a method is known where white light emitted by the device is divided into red, green, and blue lights by color filters and the following properties are required in organic EL devices used for such purposes:    i) Good balance amongst the light-emitting intensities of red, green, and blue and a resulting good whiteness;    ii) High light-emitting efficiency;    iii) Long lifetime.
As an organic EL device whose above properties are relatively good one has been proposed wherein a blue fluorescent dopant, a red phosphorescent dopant, and a green phosphorescent dopant are contained in the same light-emitting layer, for example, as seen in JP2004-14155A.
In such organic EL devices, however, the triplet energy of the red or green phosphorescent dopant moves to the triplet energy of the blue fluorescent dopant if the latter is lower than the former. In general, if a fluorescent material is brought into its triplet excited state, its energy is not used for emitting light but is consumed as heat. Thus, the blue fluorescent dopants in their triplet excited state do not emit light and are heat-deactivated. Such organic EL devices cannot achieve highly efficient light-emission or good whiteness.
An organic EL device has been proposed wherein a phosphorescent or fluorescent light-emitting dopant whose maximum-light-emission wave length is longer than that of another phosphorescent light-emitting dopant and this dopant are contained in the same light-emitting layer in, for example, JP2003-77674A.
However, in order to obtain organic EL devices whose whiteness is good, it is in fact preferred that the peak of blue be set as the maximum-light-emission wave length, so JP2003-77674A cannot achieve good whiteness. Further, since blue phosphorescent dopants have an extremely short lifetime, there is a problem in that they cannot be practically supplied.
Further, an organic EL device wherein an iridium (Ir) complex as a phosphorescent dopant is contained in a light-emitting layer has been proposed, for example, in JP2003-526876T.
This organic EL device can improve light-emission efficiency of a single color such as green, etc. but cannot improve balance amongst the light-emission intensities of red, green, and blue to achieve good whiteness.